1. Field
The present application relates generally to the operation and design of wireless devices, and more particularly, to the operation and design of low noise amplifiers.
2. Background
High quality signal reception is especially important for the current generation of portable devices. Typically, such devices provide multiple services, such as wireless communication services and, for example, position location services that require the reception of global navigation satellite signals. For example, global navigation satellite systems comprise a wide range of satellite positioning systems (SPS) that include the Global Positioning System (GPS) used in the United States, the GLObal Navigation Satellite System (GLONASS) used in Russia, the COMPASS navigation system used in China, the Galileo system used in Europe, and other regional positioning systems. Thus, the front end of a wireless receiver needs to be carefully designed to reject interfering signals and receive desired signals with high sensitivity.
To illustrate the problem, consider a GPS coexistence scenario where a portable device includes a GPS receiver and a cellular transmitter. In this GPS coexistence scenario, strong radio frequency signals can appear at the GPS receiver's front-end due to transmission on the cellular channel. Such signals may jam the GPS receiver and thus interfere with GPS signal reception. To address this problem, GPS receiver designs usually provide high linearity and have a very low noise figure (NF). Providing this high level of performance also result in high power consumption. For example, to operate concurrently during strong Tx jammer power and to avoid GPS local oscillator (LO) phase noise being mixed down to the IF Band through reciprocal mixing, the GPS LO should have very low phase noise, which may result in excessive power consumption.
Therefore, what is needed is a way to relax the LO requirements for low phase noise when strong Tx Jammer power is present in a front end receiver. It is therefore desirable to have a front end receiver with improved jammer suppression so that the LO requirements can be relaxed.